Non-cylindrical catalytic-converter carrier element and tool, and method for manufacturing it

ABSTRACT

A method for the production of a converter-carrier body having a metallic honeycomb body made of a plurality of metal layers, especially smooth layers and corrugated layers, the layers having layer ends, such that an outer shape of the honeycomb body is formed by the layer ends. At least one stack is produced having several alternately disposed metal layers that are structured such that channels are formed for a fluid to flow through. The at least one stack is transformed into a honeycomb body having a cylindrical form. The honeycomb body is deformed from the cylindrical form so that an outer shape that deviates from the cylindrical form is produced. Additionally, the invention relates to a corresponding converter-carrier body and a tool for the production thereof.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuing application, under 35 U.S.C. § 120, of copendinginternational application No. PCT/EP03/05608, filed May 28, 2003, whichdesignated the United States; this application also claims the priority,under 35 U.S.C. § 119, of German patent application No. 102 26 282.9,filed Jun. 13, 2002; the prior applications are herewith incorporated byreference in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a catalytic-converter carrier elementand a tool, and to a method for manufacturing it. Thecatalytic-converter carrier element has a metallic honeycomb elementcomposed of a plurality of smooth layers and corrugated layers withlayer ends, which are constructed such that an external shape of thehoneycomb element is formed by the layer ends. Such catalytic-convertercarrier elements are used, in particular, for cleaning exhaust gases ofmobile internal combustion engines, for example, spark ignition enginesor diesel engines, in automobile engineering. Different installationpositions have proven useful when disposing such a catalytic-convertercarrier element in the exhaust system of, for example, a passenger car.For example, catalytic-converter carrier bodies are disposed, forexample, relatively close to the internal combustion engine, inparticular, in or near to the valve outlet, in the manifold, or upstreamof an exhaust gas turbocharger. Due to the narrow spatial conditions inthe engine cavity or in its proximity, such catalytic-converter carrierelements are constructed with relatively small volumes (for example,with an overall volume that, preferably, corresponds to less than 20% ofthe cubic capacity of the internal combustion engine). Furthermore, itis known to dispose such catalytic-converter carrier elements in theregion of the underbody of a passenger car. With such a configuration ofthe catalytic-converter carrier element, it is necessary to ensure, inparticular, that the ground clearance of the automobile is not affecteddisadvantageously—to prevent the catalytic-converter carrier elementfrom coming into contact with the underlying ground. To avoid this it isalso known to countersink such catalytic-converter carrier elements atleast partially in the underbody and/or to flatten the external shape ofthe catalytic-converter carrier element.

Furthermore, when such catalytic-converter carrier elements are used inthe field of motorcycles, motorized saws, lawn mowers, or the like,particular embodiments are desired because, here, the available spacesare to be utilized as completely as possible due to the spatialconditions. This has the advantage that the previously mentioned devicescan be made very small, compact, easy-to-handle, and lightweight, thus,considerably improving the ease of operation.

An oval catalytic-converter carrier element and a method formanufacturing it are disclosed, for example, in German Published,Non-Prosecuted Patent Application DE 28 56 030 A1 (corresponding to U.S.Pat. No. 4,519,120 to Nonnenmann et al., U.S. Pat. No. 4,400,860 toNonnenmann et al., and U.S. Pat. No. 4,282,186 to Nonnenmann et al.). Tomanufacture the metallic honeycomb element, it is proposed, first, towind metal foils in a spiral shape to form a circular-cylindricalelement. To create the element, it is necessary for the ends of themetal foils on one side to be connected to a core, wherein the metalfoils are disposed around the core by turning the core. The core withthe metal foils that are wound thereon in a spiral shape is insertedsubsequently in two half shells and affixed. The core that is located inthe interior is, then, pulled out so that a hollow-cylindrical space isproduced in the center of the honeycomb element. The half shells are,then, placed together so that they abut and can be directly welded or atleast spot-welded in this position. When the half shells are placedtogether, the circular-cylindrical shape of the honeycomb element ischanged such that the honeycomb element ultimately bears uniformlyagainst the insides of the half shells. However, this requires theexternal diameter of the circular-cylindrical element and the internaldiameter of the hollow-cylindrical space of the honeycomb element tomaintain a specific relationship with one another before the half shellsare placed together.

However, the catalytic-converter carrier element that is so manufacturedand the method described in these publications have a number ofdisadvantages. For example, manufacturing the housing of thecatalytic-converter carrier element with two half shells that have to bewelded to one another is complex and costly, and the weld seam that isproduced there may be a cause of at least partial failure of thecatalytic-converter carrier element due to the high thermal and dynamicstressing that occurs in an exhaust gas system. The spiral-shapedconfiguration of the metal foils is also disadvantageous with respect tothe vibrations that occur in the exhaust system and that are due, inparticular, to the intermittent combustion process in the internalcombustion engine, which vibrations result in pressure shocks thatpropagate periodically through the exhaust system. Due to the fact thatthe metal foils have a relatively long length caused by their spiralshape and that they are attached to the housing by only one metal foilend in each case, there is the risk of telescoping, that is to say, ofthe metal foils becoming displaced with respect to one another in thedirection of flow and/or of at least parts of the metal foils becomingdetached from the housing.

In such elements, it is also necessary to take into account the factthat the metal foils are subjected to enormous thermal stresses thatresult, for example, from the temperature of the exhaust gas itself, onone hand, the temperature increasing when the catalytic-convertercarrier element is disposed more closely to the internal combustionengine. On the other hand, the chemical catalytic conversion also leadsto an increase in temperature of the catalytic-converter carrier elementbecause the element generally operates exothermally so that, undercertain circumstances, temperatures are reached that are significantlyhigher than the exhaust gas temperature itself (over 1200° C.). Both thechange in temperature and the vibration states in the exhaust systemchange at relatively high speed, which further increases the stressingof the catalytic-converter carrier element.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide anon-cylindrical catalytic-converter carrier element and tool, and methodfor manufacturing it that overcome the hereinafore-mentioneddisadvantages of the heretofore-known devices and methods of thisgeneral type and that can also be disposed in a flexible way in theexhaust system of an automobile with extremely restricted spatialconditions and that continuously withstands the thermal and dynamicstresses in the exhaust system. Furthermore, the method permits such acatalytic-converter carrier element to be manufactured easily andcost-effectively. The tool can be used to manufacture such a honeycombelement for a catalytic-converter carrier element with a non-cylindricalshape quickly, easily and economically.

With the foregoing and other objects in view, there is provided, inaccordance with the invention, a method for manufacturing acatalytic-converter carrier element, including the steps ofmanufacturing at least one stack with a plurality of alternatelydisposed sheet metal layers having layer ends, shaping the at least onestack to form a metallic honeycomb element with a cylindrical shape, thecylindrical shape of the honeycomb element being formed by the layerends, the sheet metal layers being structured to form cells throughwhich a fluid can flow, and deforming the honeycomb element to producean external shape different from the cylindrical shape.

The method according to the invention includes at least the followingsteps:

-   -   at least one stack is manufactured with a plurality of        alternately disposed sheet metal layers that are structured such        that cells through which a fluid can flow are formed;    -   the at least one stack is shaped to form a honeycomb element        with a cylindrical shape; and    -   the honeycomb element is deformed so that an external shape that        differs from the cylindrical shape is produced.

In this context, it is, first, to be noted that the honeycomb element inquestion here is not formed from metal foils that are wound on in theshape of a spiral. Instead, a plurality of sheet metal layers, inparticular, smooth layers and corrugated layers, are constructed suchthat the layer ends form the external shape of the honeycomb element.This means, in particular, that all the layer ends of the smooth layersand/or corrugated layers are disposed radially on the outside and, assuch, on one hand, delimit the external shape of the honeycomb elementand, at the same time, provide the possibility of securing each layer atboth ends to a housing. Accordingly, the telescoping of the layers, suchas can occur, in particular, with the spiral shape, is avoided. Withrespect to the configuration of such a honeycomb element, in particular,with regard to the configuration of the smooth layers and corrugatedlayers in relation to one another, reference is made at this point todocuments WO 90/03220 (corresponding to U.S. Pat. No. 5,105,539 to Mauset al., U.S. Pat. No. 5,135,794 to Maus et al., U.S. Pat. No. 5,139,844to Maus et al.), EP 0 245 737 (corresponding to U.S. Pat. No. 4,923,109to Cyron, U.S. Pat. No. 4,832,998 to Cyron, U.S. Pat. No. 4,946,822 toSwars, and U.S. Pat. No. 4,803,189 to Swars), and EP 0 831 969(corresponding to U.S. Pat. No. 6,505,396 B1 to Wieres and U.S. Pat. No.6,049,961 to Wieres), the disclosed contents of which are herebycompletely incorporated herewith by reference. These publicationsdescribe, in particular, an S-shaped, a U-shaped, and a V-shapedconfiguration of the smooth layers and corrugated layers.

After stacking the smooth layers and corrugated layers, substantiallylinear cells that extend over the entire length of the stack are formed.The at least one stack is, then, at least partially bent, wound, orwrapped so that, overall, a honeycomb element with a cylindrical shapeis formed. Cylindrical shape is understood here substantially to referto the configuration of the lateral face of the honeycomb element, whichface, preferably, include all the layer ends of the smooth layers andcorrugated layers. The fact that the stack is, first, shaped to form acylindrical element has the advantage that a relatively homogeneousstress can be brought about within the honeycomb element, and known andproven tools, devices, and methods can be used. A high level of processreliability has already been achieved with such tools, devices, andmethods within the scope of an automated fabrication system. When thehoneycomb element is manufactured with the cylindrical element, endsides that have a predefinable surface area are already defined. Thesides are substantially circular and have a specific diameter.

Then, by deforming the cylindrical element, an external shape of thehoneycomb element that differs from the cylindrical element is produced.It is necessary to take into account, in the process, the fact that thesurface area of the end faces does not change before and after thedeformation of the honeycomb element, that is to say, remainssubstantially constant. The deformation is, preferably, carried out bythe lateral face of the element so that, for example, oval, elliptical,or other external shapes are produced after the deformation. In theprocess, preferably, only an at least partial relative displacement ofthe smooth layers and corrugated layers with respect to one anothertakes place, in particular, without deformation of the cell structure orof the cell density. To ensure that, despite this relative displacementof the corrugated layers and smooth layers with respect to one another,their layer ends are disposed near to the lateral face of the honeycombelement, it is, under certain circumstances, advantageous to embody thesmooth layers and corrugated layers with different lengths (length inthe radial direction of the honeycomb element).

The previously described method is particularly simple andcost-effective. Due to the fact that the honeycomb element is deformedindependently of the housing, only small forces are necessary tomanufacture virtually any desired external shapes of thecatalytic-converter carrier element as long as certain limits ofdeformability are not exceeded. Typically deviations from thecylindrical shape of 10% to 20% of the cylinder diameter can be achievedsatisfactorily. As a result, the catalytic-converter carrier elementscan be adapted easily to the corresponding spatial conditions insmall-scale devices or in the engine compartment or near to theunderbody of an automobile. Hitherto, in the specialist field, it hadbeen assumed that the cross-sectional shape of completely filledhoneycomb elements could not be significantly deformed, but, rather,that the elements had to be manufactured directly with the desired endshape.

In accordance with another mode of the invention, the element isdeformed by a force that acts on a lateral face of the element, theforce being, preferably, applied distributed unevenly over acircumference of the lateral face. To prevent the cell structure frombeing changed or the corrugated layers from being compressed, the forceis applied initially only in a predefined circumferential section, thelayers moving out into circumferential regions that are spaced apartfrom them as a result of a relative movement between them. At the sametime, it is possible to detect a reduction in the initial diameter ofthe cylindrical shape in the direction of the application of force.

In accordance with a further mode of the invention, the element isdeformed by a tool having an input cross-section and an outputcross-section, the input cross-section being substantially circular andthe output cross-section corresponding to a cross-section with theexternal shape to be fabricated. The element is guided through the toolfrom the input cross-section to the output cross-section. The tool has aconstant internal face, here, so that the cylindrical element isconverted to the desired external shape of the honeycomb element in anon-damaging way. Such a method step is particularly simple andcost-effective because the prepared honeycomb element with itscylindrical shape merely has to be pushed through the tool or the toolhas to be guided over the honeycomb element. An elliptical, oval orother shape is, accordingly, brought about by a simple relativedisplacement of the tool and honeycomb element.

In accordance with an added mode of the invention, the smooth layers andthe corrugated layers are bent into an S shape at least in the case ofthe cylindrical element, this S-shaped configuration of the smoothlayers and corrugated layers also, preferably, being present after thedeformation of the element. With respect to the manufacture of honeycombelements with layers that are bent into an S shape, reference is made atthis point to U.S. Pat. No. 4,923,109 to Cyron, the contents of whichare hereby completely incorporated herein by reference.

In accordance with an additional mode of the invention, the cylindricalelement is only partially deformed so that the external shape thatdiffers from the cylindrical element is formed only in one region in thedirection of an axis of the honeycomb element. This means, in otherwords, that the honeycomb element has substantially a cylindrical shapein one region, while the remaining region is embodied with an externalshape that differs therefrom (oval, elliptical, or the like). In thisrespect, it is particularly advantageous that the element is guidedthrough only partially into a tool with a different inlet cross-sectionand outlet cross-section and, subsequently, led out again in theopposite direction. As a result of this fabrication step, a plurality ofdifferent external shapes can be manufactured easily.

In accordance with yet another mode of the invention, there are providedthe steps of providing a tool with an inlet cross-section and outletcross-section different from the inlet cross-section and guiding thecylindrical shape only partially into the tool in a first direction andsubsequently leading the shape out again in a second direction oppositethe first direction.

In accordance with yet a further mode of the invention, the externalshape of the honeycomb element is, then, introduced at least partiallyinto a casing tube. The casing tube, itself, is formed, preferably, inone piece, the internal boundary face corresponding substantially to theexternal shape of the honeycomb element. This means also that,preferably, all the layer ends of the smooth layers and corrugatedlayers are in contact with the casing tube so that the external shapeis, then, no longer changed.

Now, the honeycomb element that has been at least partially introducedinto the casing tube is provided with a solder and, then, subjected tothermal treatment to generate jointed connections between the smoothlayers and the corrugated layers, as well as, preferably, also betweenthe honeycomb element and the casing tube.

With the objects of the invention in view, there is also provided amethod for manufacturing a catalytic-converter carrier element includinga metallic honeycomb element constructed from a plurality of sheet metallayers having layer ends, the layer ends forming an external shape ofthe honeycomb element, including the steps of manufacturing at least onestack with a plurality of alternately disposed sheet metal layers toform a metallic honeycomb element with a cylindrical shape and to formcells through which a fluid can flow and deforming the honeycomb elementto produce an external shape different from the cylindrical shape.

With the objects of the invention in view, there is also provided acatalytic-converter carrier element, including a metallic honeycombelement having a plurality of smooth layers and corrugated layers withlayer ends forming an external shape of the honeycomb element, thesmooth and corrugated layers defining cells extending through thehoneycomb element, a first end side with a first surface area, and asecond end side with a second surface area, the first end side and thesecond end side having, in absolute terms, an identical surface area,but being non-congruent.

With the objects of the invention in view, there is also provided acatalytic-converter carrier element manufactured according to the abovemethod including a metallic honeycomb element having a plurality ofsmooth layers and corrugated layers with layer ends forming an externalshape of the honeycomb element, the smooth and corrugated layersdefining cells extending through the honeycomb element, a first end sidewith a first surface area, and a second end side with a second surfacearea, the first end side and the second end side having, in absoluteterms, an identical surface area, but being non-congruent.

According to a further aspect of the invention, a catalytic-convertercarrier element is proposed that is manufactured, in particular, usingthe method described above. This catalytic-converter carrier elementincludes a metallic honeycomb element with cells that extendtherethrough, the honeycomb element including a plurality of smoothlayers and corrugated layers with layer ends. The layers are constructedsuch that the layer ends form an external shape of the honeycomb elementand the honeycomb element has a first end side with a first surface areaand a second end side with a second surface area. Thecatalytic-converter carrier element is distinguished by the fact thatthe first end side and the second end side have, in absolute terms, anidentical surface area, but are non-congruent. This means, for example,that the first end side is oval and the second end side is circular.Both end sides have the same surface area, but the external edges of theend sides would intersect if they were superimposed directly. As alreadyexplained in the method described above, such a honeycomb element can,first, have a cylindrical region that is adjoined directly by, forexample, an oval region. Such catalytic-converter carrier elements aresuitable, in particular, to be disposed in connecting elements ofexhaust gas pipes, for example. Regions of the exhaust gas lines withchanges in the cross-sectional shape can be, then, used as acatalytically active region in the exhaust system by using such acatalytic-converter carrier element in the system.

With the objects of the invention in view, there is also provided acatalytic-converter carrier element, including a metallic honeycombelement having a stack of alternately disposed smooth sheet metal layersand corrugated sheet metal layers, the smooth and corrugated sheet metallayers having layer ends forming an external shape of the honeycombelement, the smooth and corrugated layers defining cells extendingthrough the honeycomb element through which a fluid can flow, a firstend side being substantially circular and having a first surface area,and a second end side having a second surface area equal to the firstsurface area but non-congruent thereto.

It is particularly advantageous that the catalytic-converter carrierelement has a first end face with a maximum extent and a minimum extent,and the second end face is embodied so as to be round with a constantdiameter, the maximum extent and the minimum extent differing from thediameter by 30% at maximum. The delimitation of the “incongruency” isintended to ensure that the smooth layers and corrugated layers do nottend to crease or tear during the deformation, as has been described,above, for example, with respect to the method. Embrittling of materialor work-hardening may, thus, be effectively prevented to achieve a longservice life of the catalytic-converter carrier element under the highthermal stresses later when the device is in use. For this reason, adeviation of the diameter of less than 25%, in particular, less than20%, and advantageously, less than 15% is preferred. At this point it isto be noted that the “incongruency” is not exclusively as a result offabrication tolerances, therefore, lying in the low percentage region(for example, less than 5%, preferably, less than 2%, in particular,less than 1%).

With the objects of the invention in view, there is also provided a toolfor manufacturing a metallic honeycomb element having an external shapeto be fabricated for a catalytic-converter carrier element, including atool body having an interior cavity and the interior cavity defining aninput orifice having a substantially circular input cross-section,defining an output orifice having an output cross-section correspondingto the external shape of the element to be fabricated, and defining achannel through which the element is guided through the tool from theinput cross-section to the output cross-section to convert the elementfrom a cylindrical shape into an external shape different from thecylindrical shape.

According to yet another aspect of the invention, a tool formanufacturing a metallic honeycomb element for a catalytic-convertercarrier element is proposed that is suitable for manufacturing thecatalytic-converter carrier element, in particular, in conjunction withthe method proposed above. The tool is used to convert a metallichoneycomb element with a cylindrical element into an external shape thatdiffers from it. The tool is characterized in that it is embodied withan input cross-section and an output cross-section, the inputcross-section being substantially circular and the output cross-sectioncorresponding to a cross-section with the external shape to befabricated. The honeycomb element can be guided through the tool fromthe input cross-section to the output cross-section. It is advantageous,here, that the output cross-section has a maximum width and a minimumwidth, and the input cross-section has a dimension, the maximum widthand the minimum width differing from the dimension by 30% at maximum.The internal face of the tool from the output cross-section to the inputcross-section is, preferably, continuous, that is to say, substantiallylinear contours are used to avoid excessive deformation or relativedisplacement of the smooth layers or corrugated layers. It is, undercertain circumstances, advantageous here to make the deviation of thewidths with respect to the dimensions of the input cross-section lessthan 20%, if appropriate, even less than 15%. Here, too, it is generallypossible to assume different input and output cross-sections if thedeviation between the widths has left the region of fabricationtolerances.

Other features that are considered as characteristic for the inventionare set forth in the appended claims.

Although the invention is illustrated and described herein as embodiedin a non-cylindrical catalytic-converter carrier element and tool, andmethod for manufacturing it, it is, nevertheless, not intended to belimited to the details shown because various modifications andstructural changes may be made therein without departing from the spiritof the invention and within the scope and range of equivalents of theclaims.

The construction and method of operation of the invention, however,together with additional objects and advantages thereof, will be bestunderstood from the following description of specific embodiments whenread in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of an end of a first embodiment of ahoneycomb element according to the invention with a cylindrical shape;

FIG. 2 is an elevational view of the honeycomb element of FIG. 1 with anelliptical external shape;

FIGS. 3A, 3B, 3C are diagrammatic cross-sectional views of furtherembodiments of an external shape of honeycomb elements according to theinvention;

FIGS. 4A, 4B, 4C are diagrammatic perspective views of variousalternative embodiments of an external shape of honeycomb elementsaccording to the invention;

FIG. 5 is an enlarged, diagrammatic, cross-sectional view of a detail ofa catalytic-converter carrier element according to the invention;

FIG. 6 is a plan view of a tool according to the invention;

FIG. 7 is a cross-sectional view of the tool of FIG. 6;

FIG. 8A is a fragmentary perspective view of a stack for manufacturing adeformed honeycomb element according to the method of the invention;

FIG. 8B is a diagrammatic, plan view of a tool for manufacturing adeformed honeycomb element according to the method of the invention;

FIG. 8C is a perspective view of a honeycomb element and a tool formanufacturing a deformed honeycomb element according to the method ofthe invention; and

FIG. 8D is a diagrammatic perspective view of a deformed honeycombelement formed according to the method of the invention with the toolaccording to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the figures of the drawings in detail and first,particularly to FIG. 1 thereof, there is shown a schematic plan view ofan embodiment of a honeycomb element 2 with a cylindrical shape 9. Thehoneycomb element 2 includes a plurality of smooth layers 3 andcorrugated layers 4, only one smooth layer 3 and one corrugated layer 4being illustrated by way of example in FIG. 1. The smooth layers 3 andcorrugated layers 4 are disposed around wrapping points 28, the layerends 5 of the smooth layers 3 and corrugated layers 4 all being disposedradially on the outside so that they form the lateral face 10 of thehoneycomb element 2. The honeycomb element 2 with its cylindrical shape9 has a diameter 24 and a circumference 11, and the honeycomb element 2can also be described by two main axes 29, one main axis 29 extendingthrough the wrapping points 28 and the second main axis 29 beingdisposed at an axial angle 30 of 90° with respect to the first main axis29.

While FIG. 1 represents the cylindrical shape before deformation, FIG. 2shows the external shape 6 of the honeycomb element 2 after deformation.The external shape 6 is, here, elliptical. Parallel to the main axis 29,the honeycomb element 2, then, has a maximum extent 22 and a minimumextent 23. The maximum extent 22 and the minimum extent 23 differ herefrom the diameter 24 with the cylindrical shape 9 by 30% at maximum.With the manufacturing method proposed here, it is possible tomanufacture, in particular, a honeycomb element in which it is possibleto detect a specific configuration of the wrapping points 28 in relationto the maximum extent 22 in the direction of the second main axis 29.The wrapping points 28, in fact, lie outside the second main axis 29that forms the maximum extent 22. In particular, the wrapping points 28lie outside an angle 31 of aperture of more than 10°, in particular,more than 40°, preferably, more than 90°.

FIG. 3A is a schematic view of an external shape of the honeycombelement that is referred to as “racetrack”. This shape has twosemicircles with a constant radius 32, which are connected by a linearlyextending section 34.

A further embodiment of the honeycomb element 2 is illustrated in FIG.3B, in which the external shape is formed by two, for example,elliptical edge regions that are connected to a curvature 33 by asection. The curvature 33 may be oriented here in the same direction orelse in the opposite direction (as illustrated).

FIG. 3C shows an external shape according to an oval. The external shape6 is illustrated here as a closed planar curve whose curvature ispositive overall. The opposite apex regions have different radii 32.

The external shapes 6 that are illustrated in FIGS. 3A, 3B and 3C merelyconstitute a basis for a plurality of variants that readily suggestthemselves to a person skilled in the art from the illustrations, inparticular, it is possible to combine individual features of theconfigurations shown with one another.

FIG. 4A shows a honeycomb element 2 with a cylindrical shape 9. Thehoneycomb element 2 has round end sides with a predefined surface area21. The cells 8 (not illustrated in FIG. 4A) extend between the endsides 19 and 20 substantially parallel to an axis 16.

FIG. 4B shows a deformed honeycomb element 2 with an external shape 6that has an oval cross-section.

FIG. 4C shows an only partially deformed honeycomb element 2. Near to afirst end side 19 with a first surface area 21, the honeycomb element 2has an, for example, elliptical external shape 6 over a region 15 in thedirection of the axis 16. In a region between the second end side 20with the second surface area 42 and the deformed region 15, thehoneycomb element 2 is embodied with a cylindrical shape 9.

FIG. 5 is a schematic view of a detail of an embodiment of acatalytic-converter carrier element. The boundary region between thehoneycomb element 2 and casing tube 17 is illustrated here. Thehoneycomb element 2 includes smooth layers 3 and corrugated layers 4that are disposed in the interior of the casing tube 17. Cells 8, whichextend substantially parallel to the axis 16, are formed by thestructure of the corrugated layers 4. The layers 3, 4 have jointedconnections 18 with one another, and the layers 3, 4 have jointedconnections 18 with the casing tube 17, the connections 18 beingembodied, in particular, as a soldered connection. The layers 3, 4 aregenerally high-temperature-proof and corrosion-proof metal foils(including at least the elements chromium, aluminum, iron) and each hasa layer thickness 36 that is, preferably, less than 30 μm, inparticular, less than 20 μm, and, preferably, less than 15 μm. The(metallic) casing tube 17 has a casing thickness 35 that is made greaterthan the layer thickness, in particular, the casing thickness lies in aregion from 0.8 mm to 2 mm. The cells 8 or the layers 3, 4 have acoating 37 with catalytic converters 38 that are intended to acceleratechemical conversion of the pollutants contained in the exhaust gas andinitiate this conversion even at relatively low temperatures(approximately 300° C.).

FIGS. 6 and 7 show an embodiment of a tool 12 for manufacturing acatalytic-converter carrier element 1. In the illustrated embodiment,the tool 12 is annular and has a substantially round input cross-section13 and a virtually elliptical output cross-section 14. The circularinput cross-section 13 is described unambiguously by the dimension 27.The maximum width 25 and the minimum width 26 are used to describe theelliptical shape of the output cross-section 14. The shaping ordeformation of the non-illustrated honeycomb element 2 are carried outsuch that the element 2 is initially secured by the substantiallycircular input cross-section 13 as it is pushed through the tool 12. Byvirtue of the fact that the honeycomb element is forced or pushedfurther in the direction of the arrows 39, the layers or layer ends areforced into the desired external shape by the internal face 40 of thetool 12. If the catalytic-converter carrier element that is to bemanufactured is to have a cross-section that is uniform in constructionover the entire axial length, the element is to be pushed completelythrough the tool 12 in the direction of the arrows 39 and is to beremoved at the output cross-section 14.

FIGS. 8A to 8D are schematic views of illustrating an embodiment of themethod for manufacturing a catalytic-converter carrier element 1.

In the first step shown in FIG. 8A, smooth layers 3 and corrugatedlayers 4 are alternately disposed to form a stack 7 such that cells 8through which exhaust gas can flow are formed.

Then, as illustrated in FIG. 8B, a plurality of stacks 7 is shaped intoa cylindrical honeycomb element 2 by shaped segments 41.

The cylindrical shape 9 so formed is, then, pushed through a tool 12 inthe direction of the arrows 39 (see FIG. 8C) so that an external shape 6of the honeycomb element 2 that differs from the cylindrical shape isproduced (see FIG. 8D).

According to the last step, the honeycomb element 2 with the externalshape 6 is, then, at least partially inserted into a casing tube 17 notillustrated in FIG. 8D. The catalytic-converter carrier element 1 thatis so prepared can, then, be provided with adhesive and/or solder, andits components can be aligned with one another and subjected to thermaltreatment.

1. A method for manufacturing a catalytic-converter carrier element,which comprises: manufacturing at least one stack with a plurality ofalternately disposed sheet metal layers having layer ends; shaping theat least one stack to form a metallic honeycomb element with acylindrical shape, the cylindrical shape of the honeycomb element beingformed by the layer ends, the sheet metal layers being structured toform cells through which a fluid can flow; and deforming the honeycombelement to produce an external shape different from the cylindricalshape.
 2. The method according to claim 1, which further comprisescarrying out the constructing step by constructing the honeycomb elementfrom a plurality of smooth layers and corrugated layers.
 3. The methodaccording to claim 1, wherein the honeycomb element has a lateral faceand which further comprises carrying out the deformation step with aforce acting on the lateral face.
 4. The method according to claim 1,wherein the honeycomb element has a lateral face and which furthercomprises carrying out the deformation step with application of a forcedistributed unevenly over a circumference of the lateral face.
 5. Themethod according to claim 1, which further comprises: providing a toolhaving an input cross-section and an output cross-section, the inputcross-section being substantially circular and the output cross-sectioncorresponding to a cross-section of the shape to be fabricated; andcarrying out the deformation step by guiding the honeycomb elementthrough the tool from the input cross-section to the outputcross-section.
 6. The method according to claim 2, which furthercomprises: bending the smooth and corrugated layers in an approximateS-shape at least in the cylindrical shape; and at least partly retainingthe S-shaped configuration of the smooth and corrugated layers aftercarrying out deformation of the honeycomb element.
 7. The methodaccording to claim 1, which further comprises deforming the cylindricalshape only partially to form the external shape different from thecylindrical shape only in one region in an axial direction of thehoneycomb element.
 8. The method according to claim 7, which furthercomprises providing a tool with an inlet cross-section and outletcross-section different from the inlet cross-section; and guiding thecylindrical shape only partially into the tool in a first direction andsubsequently leading the shape out again in a second direction oppositethe first direction.
 9. The method according to claim 1, which furthercomprises subsequently introducing the external shape of the honeycombelement at least partially into a casing tube.
 10. The method accordingto claim 1, which further comprises, after deforming the honeycombelement, introducing the deformed honeycomb element at least partiallyinto a casing tube.
 11. The method according to claim 9, which furthercomprises carrying out the constructing step by constructing thehoneycomb element from a plurality of smooth layers and corrugatedlayers; providing the honeycomb element at least partially introducedinto the casing tube with a solder; and subsequently subjecting theintroduced element to thermal treatment to generate jointed connectionsbetween the smooth layers and the corrugated layers.
 12. The methodaccording to claim 11, which further comprises carrying out the thermaltreatment step to generate jointed connections between the honeycombelement and the casing tube.
 13. The method according to claim 10, whichfurther comprises carrying out the constructing step by constructing thehoneycomb element from a plurality of smooth layers and corrugatedlayers; providing the honeycomb element at least partially introducedinto the casing tube with a solder; and subsequently subjecting theintroduced element to thermal treatment to generate jointed connectionsbetween the smooth layers and the corrugated layers.
 14. The methodaccording to claim 13, which further comprises carrying out the thermaltreatment step to generate jointed connections between the honeycombelement and the casing tube.
 15. A method for manufacturing acatalytic-converter carrier element including a metallic honeycombelement constructed from a plurality of sheet metal layers having layerends, the layer ends forming an external shape of the honeycomb element,which comprises: manufacturing at least one stack with a plurality ofalternately disposed sheet metal layers to form a metallic honeycombelement with a cylindrical shape and to form cells through which a fluidcan flow; and deforming the honeycomb element to produce an externalshape different from the cylindrical shape.
 16. The method according toclaim 15, which further comprises carrying out the constructing step byconstructing the honeycomb element from a plurality of smooth layers andcorrugated layers.
 17. A catalytic-converter carrier element,comprising: a metallic honeycomb element having: a plurality of smoothlayers and corrugated layers with layer ends forming an external shapeof said honeycomb element, said smooth and corrugated layers definingcells extending through said honeycomb element; a first end side with afirst surface area; and a second end side with a second surface area,said first end side and said second end side having, in absolute terms,an identical surface area, but being non-congruent.
 18. Acatalytic-converter carrier element manufactured according to the methodof claim 1, comprising: a metallic honeycomb element having: a pluralityof smooth layers and corrugated layers with layer ends forming anexternal shape of said honeycomb element, said smooth and corrugatedlayers defining cells extending through said honeycomb element; a firstend side with a first surface area; and a second end side with a secondsurface area, said first end side and said second end side having, inabsolute terms, an identical surface area, but being non-congruent. 19.A catalytic-converter carrier element, comprising: a metallic honeycombelement having: a stack of alternately disposed smooth sheet metallayers and corrugated sheet metal layers, said smooth and corrugatedsheet metal layers having layer ends forming an external shape of saidhoneycomb element, said smooth and corrugated layers defining cellsextending through said honeycomb element through which a fluid can flow;a first end side being substantially circular and having a first surfacearea; and a second end side having a second surface area equal to saidfirst surface area but non-congruent thereto.
 20. Thecatalytic-converter carrier element according to claim 17, wherein: saidfirst end side has a maximum extent and a minimum extent; said secondend side is substantially round and has a diameter; and said maximumextent and said minimum extent differ from said diameter by no more than30%.
 21. The catalytic-converter carrier element according to claim 18,wherein: said first end side has a maximum extent and a minimum extent;said second end side is substantially round and has a diameter; and saidmaximum extent and said minimum extent differ from said diameter by nomore than 30%.
 22. The catalytic-converter carrier element according toclaim 19, wherein: said first end side has a maximum extent and aminimum extent; said second end side has a diameter; and said maximumextent and said minimum extent differ from said diameter by no more than30%.
 23. A tool for manufacturing a metallic honeycomb element having anexternal shape to be fabricated for a catalytic-converter carrierelement, comprising: a tool body having an interior cavity; and saidinterior cavity: defining an input orifice having a substantiallycircular input cross-section; and defining an output orifice having anoutput cross-section corresponding to the external shape of the elementto be fabricated; and defining a channel through which the element isguided through said tool from said input cross-section to said outputcross-section to convert the element from a cylindrical shape into anexternal shape different from the cylindrical shape.
 24. The toolaccording to claim 23, wherein: said output cross-section has a maximumwidth and a minimum width; said input cross-section has a dimension; andsaid maximum width and said minimum width differ from said dimension byno more than 30%.